Bio: After Amanda Wahler destroyed the android shell in which Lex
planned to live in for all eternity, Brainiac finally revealed
that he had been operating within Luthor for years, having
placed nano bytes in his body years earlier, subtlety
influencing his decisions since he took over.

Healing Luthor of his Kryptonite induced cancer and given him
the super strength needed to defeat The Question, Brainiac
accepted Luthor's offer to live beyond his programming, and
merge into one being that would not only collect the information
it gathered, but rule it.

Having absorbed all the information from the Dark Heart,
Brainiac and Luthor created a device that they hoped would
absorb all of the information they required before the Justice
League stopped them. Having destroyed the machine, The Flash
then completely separated Luthor from Brainiac, killing him.
Given the nature of Brainiac's programming, there's no telling
whether or not he is still alive, somewhere.

Brainiac has been a mental blip in Luthor's mind ever since the two
separated. Egging Luthor on to find pieces of Brainiac so he could be
re-activated, Luthor was never successful until Tala found a vision
inside a piece of leftover Brainiac. Projecting this vision to Lex, Tala
was able to recreate Brainiac's last minutes and by this vision Luthor
was able to plot a course to it. Traveling through space, Luthor found
Brainiac's resting place, but instead of resurrecting Brainiac like he
intended, Luthor brought back a pissed off Darkseid, bonded with small
remnants of Brainiac.